The present invention relates to a semiconductor device, and more particularly, to a semiconductor integrated circuit device having a multi-wiring structure using a polyimide film as an interlevel or inter-ply insulating film.
The polyimide film has been widely used as a passivation film or an interlevel insulating film between upper and lower wiring layers. The polyimide film can be formed on a semiconductor substrate through a spin-coating method and subsequent heat treatment. It is to polymerize at a low temperature such as 400.degree. C. or less. The polyimide film, however, is apt to absorb moisture, and therefore, the polyimide film is generally covered by an insulating film such as a silicon nitride film having moisture proof nature. Owing to the silicon nitride film, failures caused by leakage current between the upper and lower wiring layers through the polyimide film, by peeling-off of the polyimide film from the lower aluminum layer and by corrosion of the lower aluminum layer by moisture can be decreased to some extent.
In the prior art semiconductor device, however, at least one small opening is provided in the silicon nitride film, and a surface portion of the polyimide film within the opening is exposed and contacted directly to a molding resin. Namely, when the silicon nitride film is selectively removed to expose the bonding areas of the bonding pads by a well-known PR method, the aperture is simultaneously formed in the silicon nitride film. In one case, the aperture is inevitably formed by an alignment mark in a photo-mask used in the PR process step, and in the other case, the aperture is intentionally formed as a production control information pattern by which an operator can recognize that the process step for exposing the bonding areas of the bonding pads has been finished and which photo-mask has been employed in the process step, etc. Sometimes both of the aperture by the alignment mark and the aperture for the production control information pattern are formed in the silicon nitride film of the semiconductor chip, The area of the aperture is very small as compared to the whole upper surface area of the semiconductor chip. However, moisture reaching the small exposed surface portion of the polyimide film within the aperture affects seriously the resin mold semiconductor device, and therefore, failures of the devices caused by problems mentioned above cannot be sufficiently decreased.